Datasheet

TL16C752B-EP

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SGLS153B –FEBRUARY 2003–REVISED DECEMBER 2007

Transmission Control Register (TCR)

The transmission control register is an 8-bit register that is used to store the receive FIFO threshold levels to

start/stop transmission during hardware/software flow control. Table 18 shows the transmission control register

bit settings.

Table 18. Transmission Control Register (TCR) Bit Settings

BIT NO. BIT SETTINGS

3:0 RCV FIFO trigger level to halt transmission (0–60)

7:4 RCV FIFO trigger level to resume transmission (0–60)

TCR trigger levels are available from 0–60 bytes with a granularity of four.

NOTE

TCR can only be written to when EFR[4] = 1 and MCR[6] = 1. The programmer must

program the TCR such that TCR[3:0] > TCR[7:4]. There is no built-in hardware check to

make sure this condition is met. Also, the TCR must be programmed with this condition

before Auto-RTS or software flow control is enabled to avoid spurious operation of the

device.

Trigger Level Register (TLR)

The trigger level register is an 8-bit register that is pulsed to store the transmit and received FIFO trigger levels

used for DMA and interrupt generation. Trigger levels from 4–60 can be programmed with a granularity of 4.

Table 19 shows the trigger level register bit settings.

Table 19. Trigger Level Register (TLR) Bit Settings

BIT NO. BIT SETTINGS

3:0 Transmit FIFO trigger levels (4–60), number of spaces available

7:4 RCV FIFO trigger levels (4–60), number of characters available

NOTE

TLR can only be written to when EFR[4] = 1 and MCR[6] = 1. If TLR[3:0] or TLR[7:4] are

0, the selectable trigger levels via the FIFO control register (FCR) are used for the

transmit and receive FIFO trigger levels. Trigger levels from 4–60 bytes are available with

a granularity of four. The TLR should be programmed for N/4, where N is the desired

trigger level.

When the trigger level setting in TLR is zero, the TL16C752B uses the trigger level setting defined in FCR. If TLR

has a nonzero trigger level value, the trigger level defined in FCR is discarded. This applies to both the transmit

FIFO and receive FIFO trigger level setting.

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